Various medical devices are known which are configured for implantation or insertion into a subject. As such theses devices have attendant mechanical requirements.
For example, balloons mounted on the distal ends of catheters are widely used in medical treatment. A balloon may be used, for example, to widen a vessel into which the catheter is inserted or to force open a blocked vessel. The requirements for the strength and size of the balloon vary widely depending on the balloon's intended use and the vessel size into which the catheter is inserted. Perhaps the most demanding applications for such balloons are in balloon angioplasty (e.g., percutaneous transluminal coronary angioplasty or “PCTA”) in which catheters are inserted for long distances into extremely small vessels and are used to open stenoses of blood vessels by balloon inflation. These applications require extremely thin-walled, high-strength balloons having predictable inflation properties. Thin walls are necessary, because the balloon's wall thickness limits the minimum diameter of the distal end of the catheter and therefore determines the ease of passage of the catheter through the vascular system and the limits on treatable vessel size. High strength is necessary because the balloon is used to push open stenoses, and the thin wall of the balloon must not burst under the high internal pressures necessary to accomplish this task (e.g., 10 to 25 atmospheres). The balloon elasticity should be relatively low (i.e., the balloon should be substantially non-compliant), so that the diameter is easily controllable (i.e., small variations in pressure should not cause wide variations in diameter, once the balloon is inflated).
As another example, intraluminal stents or stent grafts are commonly inserted or implanted into body lumens. In one common mode of implantation, the stent is provided in a compact state over an inflatable balloon. This assembly is then advanced to the desired site within a body lumen, whereupon the balloon is inflated and the stent or stent graft is expanded to support the vessel walls. In this process, the stent or stent graft is subjected to substantial forces and therefore must be mechanically robust.